<!DOCTYPE html>

<html>
<head>
  <style type="text/css" media="screen">
    .box {
      display: inline-block;
      height: 200px;
      width: 250px;
      margin: 10px;
      border: 1px solid black;
      background-repeat: no-repeat;
    }

    .gradient1 {
      background-image: radial-gradient(50% 50%, black, white);
    }

    .gradient2 {
      background-image: repeating-radial-gradient(20% 20%, black, white, black);
    }

  </style>
</head>
<body>

  <div class="gradient1 box"></div>
  <div class="gradient2 box"></div>

</body>
</html>
